When Ricker Hamilton got stung by a wasp a few years ago, he immediately began showing signs of a severe allergic reaction. It was third time in 20 years that he'd been stung and thankfully, he carried an EpiPen just in case. It probably saved his life.

When a person has an allergic reaction, it means the immune system is overreacting to something it thinks is trying to attack the body. When it works the way it should the immune system is, in a word, awesome. It protects us against all kinds of viruses and bacteria but in some people, it can go awry and attack a host of seemingly harmless substances. Allergic reactions range from mild and easily treated to severe and life-threatening. The most severe is what Ricker experienced: anaphylaxis.